• PCDDs are derivatives of dibenzo-p-dioxin. (wikipedia.org)
  • Typically, the p-dioxin skeleton is at the core of a PCDD molecule, giving the molecule a dibenzo-p-dioxin ring system. (de.tl)
  • They are mostly by-products of burning or various industrial processes or, in the case of dioxin-like PCBs and PBBs, unwanted minor components of intentionally produced mixtures. (wikipedia.org)
  • TEFs exist for seven congeners of dioxins, ten furans and twelve PCBs. (wikipedia.org)
  • Incidents of contamination with PCBs are often reported as dioxin contamination incidents since these are of most public and regulatory concern. (wikipedia.org)
  • Polychlorinated dibenzo-p-dioxins Polychlorinated dibenzofurans Polychlorinated biphenyls 1,4-dioxin Dioxins have different toxicity depending on the number and position of the chlorine atoms. (wikipedia.org)
  • Brominated dioxins and biphenyls have similar properties, but they have been studied much less. (wikipedia.org)
  • AH receptors are identified by their high-affinity binding to several carcinogenic or teratogenic environmental chemicals including polycyclic aromatic hydrocarbons found in cigarette smoke and smog, heterocyclic amines found in cooked foods, and halogenated hydrocarbons including dioxins and polychlorinated biphenyls. (lookformedical.com)
  • Dioxins and dioxin-like compounds (DLCs) are a group of chemical compounds that are persistent organic pollutants (POPs) in the environment. (wikipedia.org)
  • Because dioxins refer to such a broad class of compounds that vary widely in toxicity, the concept of toxic equivalency factor (TEF) has been developed to facilitate risk assessment and regulatory control. (wikipedia.org)
  • Dioxins (or PCDDs) have two oxygen atoms linking the two benzene rings, forming the dioxin ring. (powershow.com)
  • Dioxins are extremely stable and consequently tend to accumulate in the food chain. (wikipedia.org)
  • Dioxins are found throughout the world in the environment, and they accumulate in the food chain, mainly in the fatty tissue of animals. (wikipedia.org)
  • Dioxins accumulate in animal fat. (powershow.com)
  • Dioxins steadily accumulate in human body fat. (powershow.com)
  • They are commonly referred to as dioxins for simplicity in scientific publications because every PCDD molecule contains a dioxin skeletal structure. (de.tl)
  • Dioxins build up primarily in fatty tissues over time (bioaccumulate), so even small exposures may eventually reach dangerous levels. (de.tl)
  • There are 75 possible congeners of polychlorinated dibenzo-p-dioxins, but only 7 of them have affinity for the aryl hydrocarbon receptor (AH receptor) and are toxic via this mechanism. (wikipedia.org)
  • The reference congener is the most toxic dioxin TCDD which per definition has a TEF of one. (wikipedia.org)
  • Dioxins are highly toxic and can cause reproductive and developmental problems, damage the nervous and immune systems, interfere with hormones, and also cause cancer. (wikipedia.org)
  • Owing to the highly toxic potential of dioxins, efforts need to be undertaken to reduce current background exposure. (wikipedia.org)
  • In these regards, prevention or reduction of human exposure and a strict control of industrial processes to reduce formation of dioxins are warranted. (wikipedia.org)
  • In 1994, the US EPA reported that dioxins are a probable carcinogen, but noted that non-cancer effects (reproduction and sexual development, immune system) may pose an even greater threat to human health. (de.tl)
  • In one day a grazing cow puts as much dioxin into its body as a human being would get in 14 years of breathing (McLachlan, 1995)! (powershow.com)
  • Dioxin" can also refer to 1,4-dioxin or p-dioxin, the basic chemical unit of the more complex dioxins. (wikipedia.org)
  • Siegfried Sievers, a former Stasi member is responsible for the pollution of millions Germanys for many years with dioxins. (de.tl)
  • Analogously to PCDDs at least two lateral chlorines in each ring in positions 3,4, and/or 5 are needed for dioxin-like activity. (wikipedia.org)
  • Biggest source of dioxin is from food, particularly animal fat. (powershow.com)
  • 1949 - 1976 dioxins produced in industrial accidents in plants making 2,4,5 Trichlorophenol. (powershow.com)
  • Polychlorinated dibenzo-p-dioxins Polychlorinated dibenzofurans Polychlorinated biphenyls 1,4-dioxin Dioxins have different toxicity depending on the number and position of the chlorine atoms. (wikipedia.org)
  • There are 135 possible dibenzofurans, and 10 in which the lateral chlorines are dioxin-like. (wikipedia.org)
  • The reference congener is the most toxic dioxin TCDD which per definition has a TEF of one. (wikipedia.org)
  • In essence, multiplying the amount of a particular congener with its TEF produces the amount toxicologically equivalent to TCDD, and after this conversion all dioxin-like congeners can be summed up, and the resulting toxicity equivalent quantity (TEQ) gives an approximation of toxicity of the mixture measured as TCDD. (wikipedia.org)
  • The toxic effects of dioxins are measured in fractional equivalencies of TCDD (2,3,7,8-tetrachlorodibenzo- p -dioxin), the most toxic and best studied member of its class (see TCDD for more detailed description of the mechanism). (alchetron.com)
  • The first measurements of a congener of dioxins, 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), in biologic tissues came from Asia, based on human milk and fish samples collected in Vietnam in the early 1970s ( Baughman and Meselson 1973 ). (nih.gov)
  • Owing to the highly toxic potential of dioxins, efforts need to be undertaken to reduce current background exposure. (wikipedia.org)
  • In these regards, prevention or reduction of human exposure and a strict control of industrial processes to reduce formation of dioxins are warranted. (wikipedia.org)
  • The endocrine disrupting activity of dioxins is thought to occur as a down-stream function of AH receptor activation, with thyroid status in particular being a sensitive marker of exposure. (alchetron.com)
  • Acute effects of single high dose dioxin exposure include wasting syndrome, and typically a delayed death of the animal in 1 to 6 weeks. (alchetron.com)
  • Trends in human dioxin levels in the region cannot yet be determined, and rigorous controls are needed to reduce emissions of dioxins and human exposure in mainland China. (nih.gov)
  • The symptoms reported to be associated with dioxin toxicity in animal studies are incredibly wide ranging, both in the scope of the biological systems affected and in the range of dosage needed to bring these about. (alchetron.com)
  • By far most toxicity studies have been performed using 2,3,7,8-tetrachlorodibenzo- p -dioxin. (alchetron.com)
  • There are 75 possible congeners of polychlorinated dibenzo-p-dioxins, but only 7 of them have affinity for the aryl hydrocarbon receptor (AH receptor) and are toxic via this mechanism. (wikipedia.org)
  • While the affinity of dioxins and related industrial toxicants to this receptor may not fully explain all their toxic effects including immunotoxicity, endocrine effects and tumor promotion, toxic responses appear to be typically dose-dependent within certain concentration ranges. (alchetron.com)
  • Dioxins are highly toxic and can cause reproductive and developmental problems, damage the nervous and immune systems, interfere with hormones, and also cause cancer. (wikipedia.org)
  • Analogously to PCDDs at least two lateral chlorines in each ring in positions 3,4, and/or 5 are needed for dioxin-like activity. (wikipedia.org)
  • Dioxin" can also refer to 1,4-dioxin or p-dioxin, the basic chemical unit of the more complex dioxins. (wikipedia.org)
  • Dioxins are found throughout the world in the environment, and they accumulate in the food chain, mainly in the fatty tissue of animals. (wikipedia.org)
  • A multiphasic dose-response relationship has also been reported, leading to uncertainty and debate about the true role of dioxins in cancer rates. (alchetron.com)